The advent of digital imaging stimulated the development of Image Signal Processing (ISP) techniques to produce images that rival the quality and cost of (analog) film photography. The conventional ISP pipeline performs the basic functions: (i) correction of image capture artifacts; (ii) color image formation; (iii) image quality improvement; and (iv) image compression. The correction for radial distortion in conventional ISP pipeline, if included, is performed as one of the image quality improvement functions after color image formation.
Distortion correction is becoming increasingly more important: (i) Imaging applications demanding wider fields of view (e.g., short focal length document imaging), which drives increased distortion in cheap lens assemblies; and (ii) image sensor cost reduction pressures are driving smaller image sensor pixel sizes.
One limitation of the conventional ISP approach is that the same distortion correction is applied to all image pixel color components, even though radial distortion, for example, is proportional to wavelength.
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